Blade position control apparatus

ABSTRACT

An automatic blade position control apparatus mounted on the cutting blade of a surface finishing vehicles for maintaining the end edge thereof at a predetermined distance from a reference string and also at a predetermined height relative to the ground; said apparatus having a vertically disposed feeler arm and a horizontally presented feeler arm, both being engageable with said reference string and having a switch control arm coupled thereto for opening and closing a switch responsive to the movement of the respective feeler arms. The cutting blade is horizontally and vertically moved by hydraulic rams, of the double acting type, which rams are in circuit with the related switch and are operated responsive to the movement of said feeler arms. A parallelogram linkage assembly connects the apparatus to the vehicle for assuring proper blade endwise disposition relative to the reference string regardless of the blade angle with respect to the transverse axis of the vehicle.

Elite States Pate t 1 Gill [ Sept. 11, 1973 [73] Assignee: Westinghouse Air Brake Company,

Peoria, 111.

22 Filed: Aug. 30, 1971 211 Appl.No.: 175,885

{521 US. Cl 172/45, 37/DIG. 20, ZOO/61.44

[51] Int. Cl 1302f 3/76 [58] Field of Search 172/415; 37/DIG. 13,

[56] References Cited UNITED STATES PATENTS 3,514,630 5/1970 Steele et a1. ZOO/61.44 X 3,423,859 1/1969 Swisher et al..' 37/108 R 3,494,426 2/1970 Studebaker 172/4.5 3,619,618 11/1971 Thorn et al. 172/45 X 3,510,663 5/1970 Wyly 172/4.5 X 3,610,341 10/1971 Swisher et a1... 172/4.5 3,156,989 ll/l964 Atkinson 172/4.5 3,046,681 7/1962 Kutzler l72/4.5 3,142,915 8/1964 Curlett et al.... 172/4.5 3,044,195 7/1962 Atkinson. 172/45 3,435,546 4/1969 lverson 172/4.5 X

Primary ExaminerRobert E. Pulfrey Assistant Examiner-R. T. Rader Att0rn eyRobert J. Eck

[57] ABSTRACT An automatic blade position control apparatus mounted on the cutting blade of a surface finishing vehicles for maintaining the end edge thereof at a predetermined distance from a reference string and also at a predetermined height relative to the ground; said apparatus having a vertically disposed feeler arm and a horizontally presented feeler am, both being engageable with said reference string and having a switch control arm coupled thereto for opening and closing a switch responsive to the movement of the respective feeler arms. The cutting blade is horizontally and vertically moved by hydraulic rams, of the double acting type, which rams are in circuit with the related switch and are operated responsive to the movement of said feeler arms. A parallelogram linkage assembly connects the apparatus to the vehicle for assuring proper blade endwise disposition relative to the reference string regardless of the blade angle with respect to the transverse axis of the vehicle.

PAIENTEUSiH ima sum 1 0F 3 FIGJ INVENTOR RAYMOND E. GILL BYC ATTORNEY Pmemwsm Hm 3.157. 10

SHEET 2 BF 3 74 7) 3 4 f; V 5a 75 \1 w as a M 74 'i FIG. 4 8/ BLADE POSITION CONTROL APPARATUS BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates in general to surface finishing equipment and, more particularly, to a blade position control apparatus therefor.

Surface finishing equipment, such as graders or like vehicles with single axle steering systems, commonly use string line references to automatically guide and control the height of the cutting blade. The reference string is preset vertically to the desired profile as well as horizontally to the desired path of cut so that the cutting blade will spread and trim the earth to the same profile and path as the reference string.

The blade height adjustment devices of the prior art were of limited extent as they required the vehicle operator to steer the vehicle in close adjacency to the reference string. Understandably, if the vehicle deviated too far inwardly relative to the centerline of the path of cut, the reference string would be displaced; and if too far outwardly, the height adjustment device would be disengaged from the reference string, thereby necessitating the operator to stop the vehicle and refinish the path of cut. Therefore, it is important for the operator to maintain the height adjustment in engagement with the reference string at all times, and also, to maintain the end edge of the cutting blade a predetermined distance from the reference string for obtaining the designed depth and path of cut. In an instance when the path of cut is formed around a curve, proper blade position oftentimes is impossible, as the driver must concentrate on steering the vehicle as well as watching the reference string to be certain that he maintains the vehicle within the alloted distance.

Although many expedients have been devised for effecting the height adjustment of a cutting blade relative to the string reference, little has been done to adjust the horizontal position of the cutting blade relative to the reference string.

In most instances, the skill of the vehicle operator determined the horizontal position of the cutting blade relative to the reference string. Thus, in situations where a curvelinear path of cut was dictated, the vehicle operator, in addition to his numerous other tasks,

had to maintain a proper horizontal disposition of the cutting blade through manual precision steering.

In other instances, prior art vehicles employed complex, expensive mechanisms connected to one axle or the steering wheel and engaged to a reference string for effecting automatic steering of the vehicle. For example, some prior art vehicles were equipped with electronic steering sensors, such as a servo follower systcms, which were operated from the reference string for energizing a powered motor system, or the like, to either rotate the steering wheel or to actuate hydraulic rams connected to the vehicle axle for automatically steering the vehicle in the desired path. Such prior art automatic steering devices were costly in manufacture and extremely complicated in operation.

None of the prior art vehicles, however, incorporated a position sensing apparatus for moving the cutting blade horizontally, which operated independently of the vehicle wheel steering system. Therefore, if the cutting blade could be moved relative to the reference string, the above disadvantages could be alleviated. By

so doing, the operator would be free from his heretofore necessary manual precision steering, as the end edge of the cutting blade would be automatically maintained a predetermined distance in relation to the reference string, independent of the vehicle steering system. Consequently, the vehicle wheels may deviate from a perfect guidance path in parallel relationship to the reference string without altering the path of cut. Accordingly, the operator could devote more timeand attention to other machine operations.

By the present invention, a blade position control ap paratus is mounted on the end edge of the cutting blade, having a vertically disposed feeler arm engageable with said reference string for rockable movement inwardly and outwardly relative to the centerline of the path of cut responsive to the movement of the vehicle. The feeler arm is coupled with the switch control arm which latter opens and closes a switch connected in circuit with the hydraulic rarn for laterally moving the cutting blade transversely inwardly and outwardly a like distance as the corresponding movement of the vertical feeler arm. In this manner, the end edge of the cutting component is automatically maintained a preselected distance from the reference string at all times regardless of whether the surface finishing vehicle is traveling along a straight path or a curved path. Therefore, the more complex and expensive servo follower system components and the powered motor system can be avoided.

The coupled arrangement between the feeler arm and the switch control arm demand a minimum force against the reference string as very little friction develops on the switch control arm which moves through a light beam projected to a photoelectric switch. Thus, the apparatus of the present invention has few moving parts thereby requiring simple maintenance and being economical in manufacture and reliable and durable in usage. The blade position control apparatus of the present invention may be utilized for relatively long periods of time without adjustment and being capable of precision adjustment within 0.005 inches. Moreover, the apparatus of the present invention may be adjustable to different tolerances depending on the peculiar specifications of the particular job. Since the blade position control apparatus of the present invention is of relatively simple construction, it may be easily incorporated within existing surface finishing equipment so as to avoid costly modification and installation.-

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical transverse section taken through a surface finishing vehicle illustrating a blade position control apparatus constructed in accordance with and embodying the present invention.

FIG. 2 is a plan view taken on the line 22 of FIG. 1 illustrating the blade in another position in phantom lines. 7

FIG. 3 is a longitudinal section taken through'a position sensing apparatus of the present invention.

FIG. 4 is a longitudinal section taken on the line 44 of FIG. 3.

FIG. 5 is a transverse section taken on the line 5-5 of FIG. 3.

FIG. 6 is an electro-hydraulic schematic diagram.

FIG. 7 is a fragmentary, enlarged view of the support structure illustrated in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings wherein like reference characters designate like corresponding parts, there is shown in FIG. 1 a surface finishing vehicle 26, such as a grader or the like, comprising a frame 21 which is moveably supported above ground in the usual fashion by a plurality of wheels 22. Fixed to the forward portion of the frame 21 on each side thereof is an elevator mechanism E,E such as the customary lift mechanism 23,23, respectively, each being operatively engaged to a hydraulic ram 24,24, respectively, having an extensible and retractable piston 25,25 (FIG. 6), of the double-acting type, and a piston rod 26,26 fixed at its outer end portion to the draw bar 27. Although hydraulic rams 2 3,24 constitute the preferred embodiment for effecting the raising and lowering of the draw bar 27 and the associated'structure to be described, it will be understood that a hydraulic motor and worm gear system-may be substituted therefor.

Mounted to the under side of the draw bar 27 is the conventional circle 28 having fixed at diametrically opposed portions an arcuate support leg 29,29, each of which is connected to the mold board 30 having an elongate cutting blade 31 secured thereto and sisposed transversely of the vehicle frame 21. Fixed to the support legs 29,29 is a hydraulic ram 32, of the doubleacting type, having an extensible and retractable piston 33 (FIG. 6) and a piston rod 34 which is secured at its outer end portion to the mold board 30 adjacent the end edge 35 of said cutting blade'3ll. As will be seen hereinbelow, said hydraulic ram 32 is adapted for moving said mold board 30 and cutting blade 31 so that the end edge 35 will be maintained a specific distance, indicated d in FIGS. 1 and 2, from a reference string 36 which is secured at a predetermined grade above ground g as by the usual stakes 37 as is customarily accomplished in grading procedures.

Mounted to the rearward face of the mold board 30 in the zone substantially centrally thereof there is a horizon sensor 38, commonly referred to as a pendulum, for adjusting the slope angle of the cutting'blade 31, as will be described. Said pendulum 38 is preset at the desired angle through a cable 39 which projects upwardly for suitable attachment to a hand crank control 40 located in the region adjacent the steering wheel 41.

Mounted to the rearward face of the mold board 30 adjacent the blade end edge 35, there is a vertical leg 42 of a bracket 43 having a horizontal leg 44 located spacedly upwardly of the cutting blade upper edge 31a. Suitably fixed to the horizontal leg 44 of the bracket 43 is a support plate 45 of a bearing 46 comprising a vertical wall 47, which extends upwardly of the support plate 45, and a bearing plate 48, which is pivotally connected by a pin 49 to the support plate 45. Thus, the bearing plate 48 is rotatable about the pin 49 relative to the support plate 45 and the bracket 43. It will be noted that the axis of said pin 49 is presented in vertical alignment with the junction 50 of the blade end edge 35 and the blade lower cutting edge 31c, for purposes to be later described.

Fixed to the upper face of said bearing plate 48 is one end portion ofa support arm 51, the other end of which is fixed, as by welding, to the frame 52 of an adjustment mechanism 53. Said frame 52 is adapted for accommodating a vertically disposed screw 54 having a carriage 55, fixed thereon, which latter moves upwardly and downwardly with said screw 54 responsive to the turning thereof by a hand crank 56, as is well-known in the art.

Integrally formed with the support arm 51 there is a link 57 extending forwardly and inwardly being connected at its inner end portion by a pin 58 to an end portion of a sleeve 59 having telescopically received therein an extensible member 60. The outer end of said extensible member 60 is fixed to an end wall 61 of a support arm 62, the opposite end portion of which is fixed to the horizontal leg 44 of the bracket 43. The pin 49 is located a fixed distance y from said pin 49 for purposes to be presently seen.

Fixed to the end wall 61 of support arm 62 is one end of a cable 64, the other end of which is fixed to a vertical leg 65 of a bracket 66 having a horizontal leg 67 fixed to the circle 28 for rotation therewith. Also secured to the vertical leg 65 of bracket 66 is the outer end portion of an extensible member 68 which is telescopically received within a sleeve 69, the latter being pivotally mounted to the draw bar 27 by a spherical bearing 70 located a fixed distance x from the geometric center 71 of the circle 28. The distance x between spherical bearing 70 and the circle center 71 is in parallel relationship with and the same length as the distance y between the pin 58 and the pin 49. The support link 57, sleeve 59, extensible member 60, support arm 62, cable 64, bracket 66, extensible member 68 and sleeve 69 cooperate to establish a parallelogram linkage assembly L; the parallelogram being defined by said distances x and y and by lines connecting the pin 49 with the circle center 71 and the pin 53 with the spherical bearing 70. Through the parallelogram linkage assembly L the support structure S of the blade position control apparatus A, of the present invention will remain in the same relationship with both the cutting blade end edge 35 and the reference string 36 at all times. Moreover, a plane containing the distance y between the pins 49 and 58 of the parallelogram linkage assembly L will always be positioned in parallel relationship to the reference string 36. Thus, through the parallelogram linkage assembly L as the cutting blade 31 swings forwardly and rearwardly in accordance with the rotatable movement of the circle 28, the extensible members 60 and 68 will extend and retract through cable 64 for maintaining the end edge 35 the predetermined distance d through the actuation of hydraulic ram 32 through the blade position control apparatus A, which will now be described. The circle 28 is formed with discretely positioned detents (not shown) for limiting the rotative movement of same within a predetermined arcuate range in order to assure that the extensible members 60 and 68 will not be removed from their respective sleeves 59 and 69.

Fixed to the carriage 55 of the adjustment mechanism 53 is the support structure S for the blade position control apparatus A constituting an arm 72 which is slidably received within a sleeve 73; said arm 72 having a plurality of apertures 74 which are adapted for registering alignment with an opening 75 in the sleeve 73 whereby the relative position of the arm 72 and the sleeve 73 may be adjusted and locked into position, as by a pin (not shown). Formed integral with the sleeve 73 at the arm adjacent end thereof, there is a bracket 76 for supporting a height sensing apparatus 77 incorporating a rockably mounted feeler arm 78 with an elongate slot 78 for receiving the reference string 36; the feeler arm 78 being disposed horizontally in normal relationship to the reference string 36. Fixed to the arm remote end of sleeve 73 by a bracket 76, there is a steering sensing apparatus 79 having a rockably mounted feeler arm 80 with an elongate slot 80 for receiving the reference string 36; said feeler arm 80 being presented in vertical, normal relationship to the reference string 36. Thus, it will be observed that the feeler arms 78 and 80 of the sensing apparatuses 77 and 79 are presented in normal relationship to each other with each receiving the reference string 36.

Since both the height sensing apparatus 77 and the steering sensing apparatus 79 are identical in construction, only the steering sensing apparatus 79 will be described, it being understood that the height sensing apparatus 77 contains the identical structure and operates in a substantially identical manner.

Referring now to FIGS. 3-6 of the drawings, the steering sensing apparatus 79 comprises a housing 81 having a top wall 82, a bottom wall 83, side walls 84,84, a front end wall 85, and a rear end wall 86; said bottom wall 83 having an aperture 87 opening into a compartment 88 defined by the walls of said housing 81. Said aperture 87 is closed by a cover plate 89 for maintaining the housing 81 in a dust-proof condition. Although the aperture 87 is illustrated as being relatively large, it will be understood the same may be considerably smaller and closed with a plug or the like instead of the cover plate 89, if so desired.

Said rear wall 86 is of greater height than the housing 81 having upper and lower end portions projecting beyond the related top and bottom walls 82,83 for developing upper and lower flanges 90,90, respectively. Suitably mounted to the upper flange 90 are a pair of axially, spaced-apart light source heads 91,91, each having a cylindrical body 92,92 which is snugly received within appropriate openings (not shown) within the housing top wall 82. Each light source head 91,91 projects a beam of light 93,93, indicated in phantom lines in FIGS. 3 and 5, into said compartment 88; each 'light source head 91,91 being adjustably mounted on the upper flange 90 so that the focal pointfof the light beams 93,93 are positioned in planar alignment with the longitudinal axis of the housing 81. Said light source heads 91,91 are in circuit through leads 94,94 to a convenient source of power, such as a vehicle battery B (FIG. 6), for supplying a continuous source of power so that the light beams 93 and 93 are projected at all times during operation.

Mounted to the lower flange 90 of the housing rear wall 86 are a pair of sensing receivers 95,95, each having a cylindrical body 96,96 positioned within a suitable opening in the bottom wall 83 in axial alignment with the opposed cylindrical bodies 92,92 of the light source heads 91,91. Each of said sensing receivers 95,95 is adapted to receive said light beams 93,93, respectively, for closing a circuit, as will be seen; each sensing receiver 95,95 being connected by leads 97,97 to an amplifier 98 (FIG. 6), one side of which is connected to ground by a lead 99 and the other side to a vehicle battery B, as by a lead 100.

Spacedly rearwardly of the housing front wall 85, said top wall 82 is provided with an opening (not shown) for receiving a sleeve 101 which houses a bushing 102 interposed between upper and lower bearing assemblies 103,103, respectively, for accommodating a couple pin 104. The lower end portion of said couple pin 104 projects within the housing compartment 88 where same is fixed within a mountingblock 105 which constitutes the forward end portion of a sensor control member C presented longitudinally within the housing 81. Said sensor control member C comprises a flag arm 106 having a forward end portion 107 disposed spacedly rearwardly of the mounting block 105 and merges into a relatively narrow, elongate shank 108 having side edges 109,109 diverging outwardly endwise into flared margins 110,110 in the region adjacent said light beams 93,93, respectively. Said flared margins 110,110 terminate into a rearward end edge 111 for developing a triangular shaped tongue 112.

Secured to the underface of the forward end portion 107 of the flag arm 106, there is a block 113 having a pair of spaced-apart bores 114,114; the bore 114 being internally threaded for threadedly engaging the end portion of an adjustment screw 115, and the bore 114 being smooth for slidably accommodating the end portion of a dowel pin 1 15. Both the adjustment screw 115 and the dowel pin 115 project forwardly and outwardly of said block 113 into axially aligned bores 116,116, formed within said mounting block 105. Interposed between said blocks 105 and 113, surroundingly of the adjustment screw 115, there is a spring 117 for normally biasing said blocks 105 and 113 away from each other. Access is provided to the adjustment screw 115 through a threaded opening 118 tapped within said front end wall 85, which opening 118 is adapted to threadedly receive a removable plug 119. Thus, by removing the plug 119 and turning the adjustment screw 115, the flag arm 106 may be moved longitudinally forwardly and rearwardly within said housing compartment 88 for-altering the relative position of the flared margins 110,110 of the tongue 112 in relation to the light beams 93,93. For purposes to be presently seen, the flared margins 110,110 normally overlie the sensing receivers 95,95 so that the light beams 93,93 are blocked from being transmitted thereto.

The upper end portion of the couple pin 104 projects outwardly of the sleeve 101 for threaded engagement within a mounting block 120 having a rearward end wall 121 and a forward end wall 122, the latter having a transverse slot 123 provided therein. Received within said slot 123 is the rearward end portion of said feeler arm 80 which is maintained therein, as by conventional screws 124. The feeler arin is fabricated from a highly resilient strong material, such as fiberglass, and

' projects forwardly of the mountingblock 120 with its forward end portion being formed with a V-shaped cutout 125 which tapers inwardly and rearwarly into the elongate slot 80 for receiving the reference string 36. It will be observed that the mounting blocks 120 and are fixed to the couple pin 104 so that both the blocks and 105 will move through the same angle upon being turned. Therefore, through the positive connection between said blocks 120 and 105, the flag arm 106 will pivot about the axis of the couple pin 104 through the same angle as the feeler arm 80. Accordingly, when the feeler arm 80 is moved by its engagement with the reference string 36, said flag arm 106 will be moved through the same angle.

Fixed within said rearward end wall 121 of the mounting block 120 is a threaded shank 126 upon which is received a balance weight 127 adapted for axial movement thereon. Said balance weight 127 is maintained at a preselected position by a lock nut 128. Because of the positive connection between the feeler arm 80 and the flag arm 106, the balance therebetween may be readily adjusted by moving the balance weight 127 forwardly and rearwardly on the threaded shank 126. It will be understood that the balance weight 127 may be conveniently provided on the shank 108 of flag arm 106 if so desired with access being provided through the removable cover plate 89.

Depending on which direction the flag arm 106 is pivoted responsive to the movement of the feeler arm 80, one of said flared margins 110,110 of the tongue 112 will swing out of blocking engagement with the re-' lated light beam 93 or 93' for permitting transmittal of same to the immediately underlying sensing receiver 95 or 95 for closing a circuit. Referring to FIG. 6, the signals emitted by the sensing receivers 95,95 are transmitted to the amplifier 98 through the leads 97,97 for enhancing the emitted signal. Said amplifier 98 is connected through leads 129,129 and leads 130,130 to electrical solenoids 131,131, respectively, which soleleads, collectively designated w, to the height sensing apparatus 77. The solenoids 134, 135 are connected by leads 139,139 and leads 140,140 to an amplifier 141 being in circuit through leads, collectively designated w, to said pendulum 38.

Said spool valve 132 is in communication with said hydraulic ram 32 by conduits 142,142 which are connected to ports 143,143, respectively, located adjacent the opposed end portions of said hydraulic ram 32. Said spool valves 133,133 of master valve M are in communication with the hydraulic rams 24,24, respectively; said spool valve 133 being connected by conduits 144,145 to ports 146,147, respectively, and spool valve 133 by conduits 144,145 to ports 146,147, respectively.

Said master valve M is connected by a conduit 148 to the discharge side of a pump P, the intake side of which is connected by a conduit 150 to a reservoir 151 of hydraulic fluid, said reservoir 151 also being connected to master valve M by a return line 152. Therefore, by selective energization of solenoids 131,131, 134,134, and 135,135, through signals emitted by either the steering sensing apparatus 79, the height sensing apparatus 77 or the pendulum 38, said hydraulic rams 32,24,24, respectively, will effect the position control of cutting blade 131.

OPERATION in operation, the surface finishing vehicle 20 is locuted immediately adjacent the reference string 36 so that the latter may be received within the elongate slots 78 and 80 of feeler arms 78,80, respectively, of the respective height sensing apparatus 77 and the steering sensing apparatus 79. Thus, as the surface finishing vehicle travels along the path of cut in parallel relationship to the reference string 36, the feeler arm 80 of the height sensing apparatus 77 will move upwardly and downwardly, and the feeler arm of the steering sensing apparatus 79 will move inwardly and outwardly, relative to the reference string 36. in the event that the vehicle operator moves the vehicle in a direction away from the reference string 36, the feeler arm 80 will swing outwardly and flag arm 106 will be moved through a like angle, thereby permitting the light beam 93 to be received within the sensing receiver 95 for closing a circuit. The amplifier 98 directs the signal from the sensing receiver 95 through the leads 130,130 for energizing the solenoid 131 which establishes communication between the conduits 148 and 142 for supplying hydraulic fluid to the hydraulic ram 32. Upon entering the port 143, the fluid will push the piston 33 outwardly for moving the mold board 30 and the cutting blade 31 correspondingly outwardly untilthe tongue 112 of the flag arm 106 again blocks the light beam 93 through the return of feeler arm 80 to the proper straddling relationship with the reference string 36. The fluid within the piston rod side of said hydraulic ram 32 will pass through port 143 for return through the conduit 142 and the return line 152 to the reservoir 151. Similarly, when the feeler arm 80 is moved inwardly, as in a situation when the operator comes too close to the reference string 36, the circuit is completed through sensing receiver 95 for emitting a signal through the leads 129,129 to energize the sole noid 131, wherein fluid from reservoir 151 will be pumped through conduits 148 and 142 for pushing the piston 33 inwardly for developing a corresponding inward movement of the mold board 30 and the cutting blade 31. The fluid of the piston rod remote end of the piston 33 will be returned through the conduit 142 and the return line 152 to the reservoir 151. Thus, it will be observed that as the feeler arm 80 of the steering sensing apparatus 79 moves inwardly and outwardly as it travels along the reference string 36, the flag arm 106 will move through a like angle for opening and closing circuitsto the sensing receivers 95,95 for alternatively energizing the solenoids 131 and 131, respectively, which-effect the supply of hydraulic fluid from the reservoir 151 to the hydraulic ram 32 which, in turn, retracts and extends the piston rod 34 for moving the cutting blade 31 inwardly and outwardly accordingly. Therefore, the end edge 35 of the cutting blade 31 will be maintained at predetermined distance d from the reference string 36 at all times throughout the operation of the surface finishing vehicle 20.

Also, to change the horizontal angle of cut of the cutting blade 31, the operator will rotate the circle 28 for altering the position of the cutting blade 31 relative to the transverse axis of thevehicle. When this occurs the parallelogram linkage assembly L assures that the end edge 35 of'the cutting blade 31 will remain the predetermined distance d from the reference string 36. Assuming, for example, that the circle 28 is rotated counterclockwise, as illustrated in phantom lines in FlG.2, the extensible member 68 will be received within the sleeve 69 in the region of the circle 28 and the extensible member 60 will be extended from sleeve 59 in order to accommodate the rotation of circle 28. Therefore, no matter which direction or angle the circle 28 is rotated, the end edge 35 of the cutting blade 31 will remain a predetermined distance d from the reference string 36. I

The sensitivity of the steering sensing apparatus 79 may be altered by longitudinally adjusting the flag arm 106 within the housing compartment 88 through the adjustment screw 115 so that the flared margins 110,1 10' may be positioned at the focal pointfof both light beams 93,93. With the tongue 112 so centered, accuracy to 0.005 inches of travel of the feeler arm 80 may be accomplished. Since the work performed by the flag arm 106 passing through the light beam 93 or 93' is a frictionless operation, the steering sensing apparatus 79 offers a more reliable sensing instrument than heretofore thought possible. The accuracy of the flag arm 106 may be increased or decreased depending upon job conditions by merely turning the adjustment screw 115 to move the flared margins 110 and 110' of tongue 112 either closer to the focal pointfof the light beams 93 and 93 or further away.

in the same manner, the height sensing apparatus 77 effects the extension and retraction of said piston rod 26 of the hydraulic ram 24 for raising and lowering the cutting blade 31 adjacent the end edge 35 to adjust the height thereof. Thus, in the event that a deeper cut is dictated by a lowering of the reference string 36, relative to the ground surface g, said feeler arm 78 will be moved correspondingly downwardly for closing a circuit through the leads 137,137 to the solenoid 135 for energizing same thereby establishing communication between the conduits 148 and 144 for supplying hydraulic fluid to said hydraulic ram 24. Upon entering the hydraulic ram 24, the fluid will push the piston 25 downwardly for lowering the cutting blade 31 until the circuit is opened by the return of feeler arm 78 to the proper straddling relationship with the reference string 36. The fluid within the hydraulic ram'24 on the downward side of the piston 25 will pass through the port' 147 for return through the conduit 145 and the return line 152 to the reservoir 151. Similarly, when the feeler arm 78 is moved upwardly as it follows the reference string 36, the circuit is completed through leads 136,136 for energizing the solenoid 134 wherein fluid from the reservoir 152 will be pumped through the conduits 148 and 145 for raising the piston 25 and, hence, the cutting blade 31. The fluid on the upward side of the hydraulic ram 24 will be returned through the conduit 144 and the return line 152. to the reservoir 151.

Therefore, it will be readily observed that as the feeler arm 78 of the height sensing apparatus 77 moves upwardly and downwardly as it travels along the reference string 36, its respective flag arm will move through a like angle for opening and closing circuits through the associated sensing receivers for alternatively energizing the solenoids 134 and 135, respectively, which effect a supply of fluid to the hydraulic ram 24, which in turn retracts and extends the piston 25 for elevating and lowering the cutting blade 31. Accordingly, the proper height of the cutting blade 31 may be achieved at all times throughout the operation of the surface finishing vehicle 20.

The pendulum 38 is in circuit with the solenoid 134 and 135' of spool valve 133 for effecting the extension and retraction of the piston rod 26' of the hydraulic ram 24. Accordingly, the pendulum 38 operates to raise and lower the cutting blade 31 through the associated structure to alter the angle with respect to the horizontal of the cutting blade 31. Since the pendulum 38 does not form a part of the present invention, a detailed description and operation of the same is unnecessary.

Therefore, by the present invention, the position of the cutting blade 31 may be automatically controlled for maintaining its end edge 35 a predetermined distance d from the reference string 36 at all times through the steering sensing apparatus 79 and also for maintaining the cutting blade 31 at desired height in accordance with the preset grade and angle through the height sensing apparatus 77 and the pendulum 38, respectively. Accordingly, the proper positionment of the cutting blade 31 may be automatically maintained at all times requiring virtually no attention of the vehicle operator after the blade control position apparatus A and the pendulum 38 have been properly preset.

Having thus described my invention, what I claim and desire to obtain by Letters Patent is:

1. A surface finishing vehicle of the type used for moving earth in accordance with a reference string comprising:

A mobile frame adapted for travel substantially parallel to said reference string;

A cutting blade disposed transversely of said frame;

Means adjustably supporting said cutting blade from said frame including a circle member adapted for rotational movement about a vertical axis;

Actuator means associated withsaid cutting blade for moving same transversely inwardly and outwardly relative to said frame;

A steering sensing apparatus for said cutting blade including a rockably mounted feeler member having a slot for receiving said reference string;

Support means mounting said steering sensing apparatus on said cutting blade;

Sensor means;

, Means operatively connecting said sensor means and said actuator means; Sensor control means associated with said feeler member for energizing said sensor means responsive to the rockable movement of said feeler member to steer said cutting blade independently of said frame for maintaining same in a preselected position relative to said reference string;

Linkage means connectingsaid support means with said circle and said vehicle frame for maintaining said steering sensing apparatus in predetermined attitude relative to the reference string during the rotational movement of said circle member and said cutting blade;

Said support means comprising a fixed component and a swingable component;

said swingable component carrying said steering sensing apparatus;

bearing means pivotally connecting said swingable component to said fixed component;

said linkage means comprising a first extensible member having end portions, one end portion being pivotally connected to said swingable component and the other end portion being fixed to said fixed component;

a second extensible member having end portions, one end portion being pivotally connected to said frame and the other end portion being fixed to said circle member; I

cable means interconnecting said first and second extensible members;

said first and second extensible members and said cable means cooperating to maintain said steering sensing apparatus in predetermined attitude relative to said reference string during rotational movement of said circle member and said cutting blade.

2. A surface finishing vehicle of the type used for moving earth in accordance with a reference string comprising:

a mobile frame adapted for travel substantially parallel to said reference string;

a cutting blade disposed transversely of said frame;

means adjustably supporting said cutting blade from said frame;

actuator means associated with said cutting blade for moving same transversely inwardly and outwardly relative to said frame;

a position sensing apparatus including a rockably mounted feeler member having a slot for receiving said reference string;

sensor means;

means connecting said sensor means and said actua- I tor means;

sensor control means associated with said feeler member for energizing said sensor means responsive to the rockable movement of said feeler member;

support means connecting'said position sensing apparatus to said cutting blade;

said support means comprising a fixed component and a swingable component;

bearing means pivotally connecting said swingable component to said fixed component;

said swingable component having first and second end portions;

said first end portion carrying said position sensing apparatus;

a first extensible member having a sleeve and a rod telescopicly received within said sleeve; 7

means pivotally connecting said sleeve with said second end portion of said swingable component;

means fixing said rod to said fixed component;

cable means connecting said first extensible member to said means adjustably supporting said cutting blade to said frame.

3. A surface finishing vehicle as defined in claim 2 and further characterized by:

Said means adjustably supporting said cutting blade from said frame including a circle member having a center and adapted for rotational movement about said center;

A second extensible member comprising a second sleeve and a second rod telescopically received within said second sleeve;

Means pivotally connecting said second sleeve to said frame at a spaced distance from said circle center;

Means fixing said second rod to said circle for rotation therewith;

Said cable means interconnecting said first and second rods. I

4. A surface finishing vehicle as defined in claim 3 and further characterized by:

The axes of said bearing means and said means pivotally connecting said first sleeve with said swingable component being disposed in a vertical plane presented in parallel relationship with a vertical plane containing the axes of said circle center and the means pivotally connecting said second sleeve to said frame.

5. A surface finishing vehicle as defined in claim 3 and further characterized by:

The axes of said bearing means and said circle center being disposed in a vertical plane presented in parallel relationship with a vertical plane containing the axes of the said means pivotally connecting said first sleeve with the second end portion of said swingable component and said second sleeve to the vehicle frame.

6. A surface finishing vehicle as defined in claim 2 and further characterized by:

Said cutting blade having a cutting edge, an end edge and ajunction joining the cutting edge and the end edge 7 The axis of said bearing means being in vertical alignment with the junction of the cutting edge and the end edge of said cutting blade;

Said first and second extensible members and said cable means cooperating to maintain said junction a predetermined distance from the reference string.

7. For use with a cutting tool having an end edge, an

apparatus for automatically maintaining the end edge of a cutting tool a predetermined distance from a reference string comprising:

sor control arm being normally presented between.

said light projecting means and said first and second light responsive switches for maintaining same in a circuit-opened condition; I

a rockablymounted feeler member having an elongate slot for receiving said reference string, said feeler member being disposed exteriorly of said housing in planar parallel spaced-apart relationship with said sensor control arm;

7 means coupling said sensor control arm to said feeler member for effecting simultaneous movement therewith. I 8. An apparatus as defined in claim 7 and further characterized by:

said sensor control arm having a first end portion and a second end portion;

said coupling means fixing the first end portion of said sensor control arm to said feeler member;

each first and second light responsive switches having a center; v

the second end portion if said sensor control arm being normally presented between said light projecting means and said first and secondlight responsive switches, said second end portion having a width greater than the distance between the centers of said first and second light responsive switches.

9. An apparatus as defined in claim 8 and further characterized by:

said sensor control arm having side edges;

the second end portion of said sensor control arm having margins diverging outwardly of said side edges for defining a triangular-shaped tongue;

said tongue being normally presented in blocking relationship between said light projecting means and said first and second light responsive switches.

10. An apparatus as defined in claim 9 and further characterized by:

adjustment means on said sensor control arm for moving same longitudinally within said housing relative to said first and second light responsive switches.

11. An apparatus as defined in claim 7 and further characterized by:

Balance means mounted on said feeler member for maintaining said sensor control arm in a plane disposed in normal relationship to a plane containing the axes of said first and second light responsive switches.

12. A surface finishing vehicle of the type used for moving earth in accordance with a reference string comprising:

a mobile frame adapted for travel substantially parallel to said reference string;

a cutting blade disposed transversely of said frame;

means adjustably supporting said cutting blade from said frame including a circle member adapted for rotational movement about a vertical axis;

actuator means associated with said cutting blade for moving same transversely inwardly and outwardly relative to said frame;

a steering sensing apparatus for said cutting blade including a rockably mounted feeler member having a slot for receiving said reference string;

support means pivotally mounting said steering sensing apparatus on said cutting blade;

sensor means;

means operatively connecting said sensor means and said actuator means;

sensor control means associated with said feeler member for energizing said sensor means responsive to the rockable movement of said feeler member;

linkage means connecting said support means with said circle member and said vehicle frame for simultaneously maintaining: said steering sensing apparatus in predetermined attitude relative to the reference string; and the end edge of said cutting blade in predetermined spacial relationship to the reference string, during the rotational movement of said circle member and said cutting blade. 

1. A surface finishing vehicle of the type used for moving earth in accordance with a reference string comprising: A mobile frame adapted for travel substantially parallel to said reference string; A cutting blade disposed transversely of said frame; Means adjustably supporting said cutting blade from said frame including a circle member adapted for rotational movement about a vertical axis; Actuator means associated with said cutting blade for moving same transversely inwardly and outwardly relative to said frame; A steering sensing apparatus for said cutting blade including a rockably mounted feeler member having a slot for receiving said reference string; Support means mounting said steering sensing apparatus on said cutting blade; Sensor means; Means operatively connecting said sensor means and said actuator means; Sensor control means associated with said feeler member for energizing said sensor means responsive to the rockable movement of said feeler member to steer said cutting blade independently of said frame for maintaining same in a preselected position relative to said reference string; Linkage means connecting said support means with said circle and said vehicle frame for maintaining said steering sensing apparatus in predetermined attitude relative to the reference string during the rotational movement of said circle member and said cutting blade; Said support means comprising a fixed component and a swingable component; said swingable component carrying said steering sensing apparatus; bearing means pivotally cOnnecting said swingable component to said fixed component; said linkage means comprising a first extensible member having end portions, one end portion being pivotally connected to said swingable component and the other end portion being fixed to said fixed component; a second extensible member having end portions, one end portion being pivotally connected to said frame and the other end portion being fixed to said circle member; cable means interconnecting said first and second extensible members; said first and second extensible members and said cable means cooperating to maintain said steering sensing apparatus in predetermined attitude relative to said reference string during rotational movement of said circle member and said cutting blade.
 2. A surface finishing vehicle of the type used for moving earth in accordance with a reference string comprising: a mobile frame adapted for travel substantially parallel to said reference string; a cutting blade disposed transversely of said frame; means adjustably supporting said cutting blade from said frame; actuator means associated with said cutting blade for moving same transversely inwardly and outwardly relative to said frame; a position sensing apparatus including a rockably mounted feeler member having a slot for receiving said reference string; sensor means; means connecting said sensor means and said actuator means; sensor control means associated with said feeler member for energizing said sensor means responsive to the rockable movement of said feeler member; support means connecting said position sensing apparatus to said cutting blade; said support means comprising a fixed component and a swingable component; bearing means pivotally connecting said swingable component to said fixed component; said swingable component having first and second end portions; said first end portion carrying said position sensing apparatus; a first extensible member having a sleeve and a rod telescopicly received within said sleeve; means pivotally connecting said sleeve with said second end portion of said swingable component; means fixing said rod to said fixed component; cable means connecting said first extensible member to said means adjustably supporting said cutting blade to said frame.
 3. A surface finishing vehicle as defined in claim 2 and further characterized by: Said means adjustably supporting said cutting blade from said frame including a circle member having a center and adapted for rotational movement about said center; A second extensible member comprising a second sleeve and a second rod telescopically received within said second sleeve; Means pivotally connecting said second sleeve to said frame at a spaced distance from said circle center; Means fixing said second rod to said circle for rotation therewith; Said cable means interconnecting said first and second rods.
 4. A surface finishing vehicle as defined in claim 3 and further characterized by: The axes of said bearing means and said means pivotally connecting said first sleeve with said swingable component being disposed in a vertical plane presented in parallel relationship with a vertical plane containing the axes of said circle center and the means pivotally connecting said second sleeve to said frame.
 5. A surface finishing vehicle as defined in claim 3 and further characterized by: The axes of said bearing means and said circle center being disposed in a vertical plane presented in parallel relationship with a vertical plane containing the axes of the said means pivotally connecting said first sleeve with the second end portion of said swingable component and said second sleeve to the vehicle frame.
 6. A surface finishing vehicle as defined in claim 2 and further characterized by: Said cutting blade having a cutting edge, an end edge and a junction joining the cutting edge and the end Edge The axis of said bearing means being in vertical alignment with the junction of the cutting edge and the end edge of said cutting blade; Said first and second extensible members and said cable means cooperating to maintain said junction a predetermined distance from the reference string.
 7. For use with a cutting tool having an end edge, an apparatus for automatically maintaining the end edge of a cutting tool a predetermined distance from a reference string comprising: said cutting tool having actuator means for laterally moving same inwardly and outwardly relative to said reference string; means defining a housing mounted on said cutting tool; sensor means within said housing being operatively connected to said actuator means, said sensor means comprising: light projecting means, and first and second light responsive switches in circuit with said actuator means and presented within said housing in aligned relationship with said light projecting means; a sensor control arm rockably mounted within said housing for energizing said sensor means, said sensor control arm being normally presented between said light projecting means and said first and second light responsive switches for maintaining same in a circuit-opened condition; a rockably mounted feeler member having an elongate slot for receiving said reference string, said feeler member being disposed exteriorly of said housing in planar parallel spaced-apart relationship with said sensor control arm; means coupling said sensor control arm to said feeler member for effecting simultaneous movement therewith.
 8. An apparatus as defined in claim 7 and further characterized by: said sensor control arm having a first end portion and a second end portion; said coupling means fixing the first end portion of said sensor control arm to said feeler member; each first and second light responsive switches having a center; the second end portion if said sensor control arm being normally presented between said light projecting means and said first and second light responsive switches, said second end portion having a width greater than the distance between the centers of said first and second light responsive switches.
 9. An apparatus as defined in claim 8 and further characterized by: said sensor control arm having side edges; the second end portion of said sensor control arm having margins diverging outwardly of said side edges for defining a triangular-shaped tongue; said tongue being normally presented in blocking relationship between said light projecting means and said first and second light responsive switches.
 10. An apparatus as defined in claim 9 and further characterized by: adjustment means on said sensor control arm for moving same longitudinally within said housing relative to said first and second light responsive switches.
 11. An apparatus as defined in claim 7 and further characterized by: Balance means mounted on said feeler member for maintaining said sensor control arm in a plane disposed in normal relationship to a plane containing the axes of said first and second light responsive switches.
 12. A surface finishing vehicle of the type used for moving earth in accordance with a reference string comprising: a mobile frame adapted for travel substantially parallel to said reference string; a cutting blade disposed transversely of said frame; means adjustably supporting said cutting blade from said frame including a circle member adapted for rotational movement about a vertical axis; actuator means associated with said cutting blade for moving same transversely inwardly and outwardly relative to said frame; a steering sensing apparatus for said cutting blade including a rockably mounted feeler member having a slot for receiving said reference string; support means pivotally mounting said steering sensing apparatus on said cutting blade; sensor means; means operatIvely connecting said sensor means and said actuator means; sensor control means associated with said feeler member for energizing said sensor means responsive to the rockable movement of said feeler member; linkage means connecting said support means with said circle member and said vehicle frame for simultaneously maintaining: said steering sensing apparatus in predetermined attitude relative to the reference string; and the end edge of said cutting blade in predetermined spacial relationship to the reference string, during the rotational movement of said circle member and said cutting blade. 